However it turns out that, in some enlarged conceptual framework, the answers to both questions are positive and rely on the same ideas. The key was the introduction by A. Salam and J. Strathdee of anticommuting coordinate variables (also called Grassmann variables), which one could heuristically think as classical limits of Fermionic operators. This leads to a theory of superspaces or supermanifolds, proposed by J. Wess and B. Zumino and developped by F. Berezin, B. DeWitt, A. Rogers in which the `classical limit' of the symmetry between Bosons and Fermions admits a geometric formulation. In this framework one can also extend the Lie algebra of the Poincaré group into a super Lie algebra, as done by Y.A. Gol'fand and E.P. Likhtman [1]} and D. Volkov and V. Akulov [2]}. The mathematical theory of Lie super algebra and Lie super groups was then constructed by V. Kac [3]}.
